The present invention relates to a defect inspection method and a defect inspection device inspecting a minute defect existing in the surface of a sample with high sensitivity.
Thin film devices such as semiconductor wafers, liquid crystal displays, and hard disk magnetic heads, are manufactured through a number of processes. In manufacturing these thin film devices, an appearance inspection is carried out in each series of processes for improving the yield and achieving stabilization.
Patent Literature 1 (Japanese Patent No. 3566589) discloses a method “which detects a pattern defect or a defect such as foreign substance based on a three-illuminated image and an inspection image that are obtained by using lamp light, laser light, or an electron beam, for corresponding areas in two patterns formed to have the same shape in the appearance inspection.”
As a technique for improving the inspection sensitivity, Patent Literature 2 (U.S. Pat. No. 7,221,992) and Patent Literature 3 (U.S. Patent Publication No. 2008/285023) disclose “a method which simultaneously detects images under a plurality of different optical conditions, compares the brightness of them with a three-illuminated image for each of the conditions, and integrates the comparison values to determine a defect and a noise.”
On the other hand, in order to integrate images of a plurality of optical conditions, the images have to be aligned with one another. Patent Literature 4 (Japanese Patent Application Laid-Open No. 2008-268199) discloses “a method which calculates the position deviation amounts of the respective images in advance by using a standard sample or the like and uses those position deviation amounts for alignment.” Patent Literature 5 (Japanese Patent Application Laid-Open No. 2003-83907) discloses a method for correcting color unevenness, position deviation, and image distortion in inspection object images.